Shania Twain's Engagement Ring: All the Details!

Shania Twain looked especially dazzling at Serafina's Fabulous Grill in NYC on Dec. 16. A witness tells Us the singer, 45, and her brand-new fiance Frederic Thiebaud were "super cuddly" as they sipped champagne and dined on pasta and salads.

Nearly stealing the show from the superstar? The huge diamond engagement ring on her finger.

"Shania was glowing while showing off her ring," another onlooker tells Us. When a fellow Serafina's patron noticed the sparkler and congratulated Twain on the engagement, she lit up and replied, "Thank you!"

Nestle executive Thiebaud, 40, proposed to Twain in Switzerland two months ago with the eye-catching bauble -- and worked directly with famed jeweler Lorraine Schwartz to design it.

A day after UsMagazine.com broke the news, Twain confirmed her engagement with a heartfelt letter to fans Tuesday.

"I'm in love!" she wrote "Frederic Nicolas Thiebaud has been a true gift to me as a compassionate, understanding friend and over time, an amazing love has blossomed from this precious friendship. Fred and I are happy to announce, our ENGAGEMENT!"

Thiebaud is ex-husband to Twain's ex-BFF Marie-Anne Thiebaud -- the woman Robert "Mutt" Lange, Twain's husband of 14 years, abruptly left her for in May 2008. She and Frederic became close in the aftermath of their shocking divorces.